1. Field of the Invention
The present invention relates to an information memory medium, and more particularly to an optical recording disk used for an information processing apparatus for recording, reproducing or erasing image information.
2. Discussion of Background
Recently, information processing apparata having used as an information memory medium an optical recording disk for recording or reproducing image information.
In the information processing apparatus of this type, the optical recording disk is mounted on a turntable and rotated so that the apparatus may perform information processing, such as recording or reproduction, on or from the optical recording disk. In order to support the optical recording disk on the turntable in the information processing apparatus, the optical recording disk is magnetically attracted by a magnetic attraction member provided on the turntable. The magnetic attraction member attracts an attractable member which is disposed on a central portion of the outside surface of the optical recording disk. The optical recording disk has a label denoting the manufacturer, recording sides, such as sides A and B, and the type of the disk. Also, the label is attached to the outside surface of the central portion of the substrate. Generally, a layer of an adhesive agent used to bond the label to the substrate does not have an uniform thickness along its surface. Also, the thickness of the label is itself not uniform. Therefore, the optical recording disk, provided with the attractable member installed on the label on the substrate, does not present a uniform attraction force to the attractable member. Consequently, the optical recording disk may not be mounted on the turntable stably, so that information may not be correctly recorded or reproduced.
In the above-described arrangement of the attractable member and the turntable, it is very difficult to prevent the optical recording disk from vibrating because the attractable member and the substrate do not have accurately parallel surfaces facing each other. The apparatus, therefore, is arranged such that the substrate of the optical recording disk is adapted to oppose the surface of the turntable. However, if the label, which is attached to the central portion of the outside surface of the substrate, is in directd contact with the surface of the turntable, the optical recording disk is slightly vibrated. Therefore, information may not be correctly recorded or reproduced on or form the optical recording disk.